<template>
  <div
    class="slide-verify"
    :style="{ width: w + 'px' }"
    id="slideVerify"
    onselectstart="return false;"
    @click.stop=""
  >
    <!-- 图片加载遮蔽罩 -->
    <div :class="{ 'slider-verify-loading': loadBlock }"></div>
    <canvas :width="w" :height="h" ref="canvas"></canvas>
    <div v-if="show" @click="refresh" class="slide-verify-refresh-icon"></div>
    <canvas
      :width="w"
      :height="h"
      ref="block"
      class="slide-verify-block"
    ></canvas>
    <!-- container -->
    <div
      class="slide-verify-slider"
      :class="{
        'container-active': containerActive,
        'container-success': containerSuccess,
        'container-fail': containerFail
      }"
    >
      <div class="slide-verify-slider-mask" :style="{ width: sliderMaskWidth }">
        <!-- slider -->
        <div
          @mousedown="sliderDown"
          @touchstart="touchStartEvent"
          @touchmove="handleMoveEvent($event, 'touch')"
          @touchend="handleMoveEndEvent($event, 'touch')"
          class="slide-verify-slider-mask-item"
          :style="{ left: sliderLeft }"
        >
          <div class="slide-verify-slider-mask-item-icon"></div>
        </div>
      </div>
      <span class="slide-verify-slider-text">{{ sliderText }}</span>
    </div>
  </div>
</template>
<script>
const PI = Math.PI;

function sum(x, y) {
  return x + y;
}

function square(x) {
  return x * x;
}
export default {
  name: "SlideVerify",
  props: {
    // block length
    l: {
      type: Number,
      default: 42
    },
    // block radius
    r: {
      type: Number,
      default: 10
    },
    // canvas width
    w: {
      type: Number,
      default: 310
    },
    // canvas height
    h: {
      type: Number,
      default: 155
    },
    sliderText: {
      type: String,
      default: "Slide filled right"
    },
    accuracy: {
      type: Number,
      default: 5 // 若为 -1 则不进行机器判断
    },
    show: {
      type: Boolean,
      default: true
    },
    imgs: {
      type: Array,
      default: () => []
    }
  },
  data() {
    return {
      containerActive: false, // container active class
      containerSuccess: false, // container success class
      containerFail: false, // container fail class
      canvasCtx: null,
      blockCtx: null,
      block: null,
      block_x: undefined, // container random position
      block_y: undefined,
      L: this.l + this.r * 2 + 3, // block real length
      img: undefined,
      originX: undefined,
      originY: undefined,
      isMouseDown: false,
      trail: [],
      sliderLeft: 0, // block right offset
      sliderMaskWidth: 0, // mask width,
      success: false, // Bug Fixes 修复了验证成功后还能滑动
      loadBlock: true, // Features 图片加载提示，防止图片没加载完就开始验证
      timestamp: null
    };
  },
  mounted() {
    this.init();
  },
  methods: {
    init() {
      this.initDom();
      this.initImg();
      this.bindEvents();
    },
    initDom() {
      this.block = this.$refs.block;
      this.canvasCtx = this.$refs.canvas.getContext("2d");
      this.blockCtx = this.block.getContext("2d");
    },
    initImg() {
      const img = this.createImg(() => {
        // 图片加载完关闭遮蔽罩
        this.loadBlock = false;
        this.drawBlock();
        this.canvasCtx.drawImage(img, 0, 0, this.w, this.h);
        this.blockCtx.drawImage(img, 0, 0, this.w, this.h);
        let { block_x: x, block_y: y, r, L } = this;
        let _y = y - r * 2 - 1;
        let ImageData = this.blockCtx.getImageData(x, _y, L, L);
        this.block.width = L;
        this.blockCtx.putImageData(ImageData, 0, _y);
      });
      this.img = img;
    },
    drawBlock() {
      this.block_x = this.getRandomNumberByRange(
        this.L + 10,
        this.w - (this.L + 10)
      );
      this.block_y = this.getRandomNumberByRange(
        10 + this.r * 2,
        this.h - (this.L + 10)
      );
      this.draw(this.canvasCtx, this.block_x, this.block_y, "fill");
      this.draw(this.blockCtx, this.block_x, this.block_y, "clip");
    },
    draw(ctx, x, y, operation) {
      let { l, r } = this;
      ctx.beginPath();
      ctx.moveTo(x, y);
      ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI);
      ctx.lineTo(x + l, y);
      ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI);
      ctx.lineTo(x + l, y + l);
      ctx.lineTo(x, y + l);
      ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true);
      ctx.lineTo(x, y);
      ctx.lineWidth = 2;
      ctx.fillStyle = "rgba(255, 255, 255, 0.7)";
      ctx.strokeStyle = "rgba(255, 255, 255, 0.7)";
      ctx.stroke();
      ctx[operation]();
      // Bug Fixes 修复了火狐和ie显示问题
      ctx.globalCompositeOperation = "destination-over";
    },
    createImg(onload) {
      const img = document.createElement("img");
      img.crossOrigin = "Anonymous";
      img.onload = onload;
      img.onerror = () => {
        img.src = this.getRandomImg();
      };
      img.src = this.getRandomImg();
      return img;
    },
    // 随机生成img src
    getRandomImg() {
      // return require('../assets/img.jpg')
      const len = this.imgs.length;
      //console.log("this.imgs:",this.imgs);
      // 这里判断是否传入图片 负责使用随机图片
      // 下面的网络图片需要翻墙
      // 比如 https://picsum.photos/300/150/?image=1084
      return len > 0
        ? this.imgs[this.getRandomNumberByRange(0, len - 1)]
        : "https://picsum.photos/300/150/?image=" +
            this.getRandomNumberByRange(0, 1084);
    },
    getRandomNumberByRange(start, end) {
      return Math.round(Math.random() * (end - start) + start);
    },
    refresh() {
      this.reset();
      this.$emit("refresh");
    },
    sliderDown(event) {
      if (this.success) return;
      this.originX = event.clientX;
      this.originY = event.clientY;
      this.isMouseDown = true;
      this.timestamp = +new Date();
    },
    touchStartEvent(e) {
      if (this.success) return;
      this.originX = e.changedTouches[0].pageX;
      this.originY = e.changedTouches[0].pageY;
      this.isMouseDown = true;
      this.timestamp = +new Date();
    },
    bindEvents() {
      document.addEventListener("mousemove", this.handleMoveEvent);
      document.addEventListener("mouseup", this.handleMoveEndEvent);
    },
    // 处理函数抽离
    handleMoveEvent: throttle(function(e, type = "mouse") {
      if (!this.isMouseDown) return false;
      const moveX =
        type === "mouse"
          ? e.clientX - this.originX
          : e.changedTouches[0].pageX - this.originX;
      const moveY =
        type === "mouse"
          ? e.clientY - this.originY
          : e.changedTouches[0].pageY - this.originY;
      if (moveX < 0 || moveX + 38 >= this.w) return false;
      this.sliderLeft = moveX + "px";
      let blockLeft = ((this.w - 40 - 20) / (this.w - 40)) * moveX;
      this.block.style.left = blockLeft + "px";

      this.containerActive = true; // add active
      this.sliderMaskWidth = moveX + "px";
      this.trail.push(moveY);
    }),
    handleMoveEndEvent(e, type = "mouse") {
      if (!this.isMouseDown) return false;
      this.isMouseDown = false;
      if (
        (type === "mouse" && e.clientX === this.originX) ||
        (type === "touch" && e.changedTouches[0].pageX === this.originX)
      )
        return false;
      this.containerActive = false; // remove active
      this.timestamp = +new Date() - this.timestamp;

      const { spliced, TuringTest } = this.verify();
      if (spliced) {
        if (this.accuracy === -1) {
          this.containerSuccess = true;
          this.success = true;
          this.$emit("success", this.timestamp);
          return;
        }
        if (TuringTest) {
          // succ
          this.containerSuccess = true;
          this.success = true;
          this.$emit("success", this.timestamp);
        } else {
          this.containerFail = true;
          this.$emit("again");
        }
      } else {
        this.containerFail = true;
        this.$emit("fail");
        setTimeout(() => {
          this.reset();
        }, 1000);
      }
    },
    verify() {
      const arr = this.trail; // drag y move distance
      const average = arr.reduce(sum) / arr.length; // average
      const deviations = arr.map(x => x - average); // deviation array
      const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length); // standard deviation
      const left = parseInt(this.block.style.left);
      const accuracy =
        this.accuracy <= 1 ? 1 : this.accuracy > 10 ? 10 : this.accuracy;
      return {
        spliced: Math.abs(left - this.block_x) <= accuracy,
        TuringTest: average !== stddev // equal => not person operate
      };
    },
    reset() {
      this.success = false;
      this.containerActive = false;
      this.containerSuccess = false;
      this.containerFail = false;
      this.sliderLeft = 0;
      this.block.style.left = 0;
      this.sliderMaskWidth = 0;
      // canvas
      let { w, h } = this;
      this.canvasCtx.clearRect(0, 0, w, h);
      this.blockCtx.clearRect(0, 0, w, h);
      this.block.width = w;

      // generate img
      this.img.src = this.getRandomImg();
      this.$emit("fulfilled");
    }
  },
  destroyed() {
    document.removeEventListener("mousemove", this.handleMoveEvent);
    document.removeEventListener("mouseup", this.handleMoveEndEvent);
  }
};

function throttle(
  fn,
  interval = 50,
  options = { leading: true, trailing: true }
) {
  const { leading, trailing, resultCallback } = options;
  let lastTime = 0;
  let timer = null;

  const _throttle = function(...args) {
    return new Promise((resolve, reject) => {
      const nowTime = new Date().getTime();
      if (!lastTime && !leading) lastTime = nowTime;

      const remainTime = interval - (nowTime - lastTime);
      if (remainTime <= 0) {
        if (timer) {
          clearTimeout(timer);
          timer = null;
        }

        const result = fn.apply(this, args);
        if (resultCallback) resultCallback(result);
        resolve(result);
        lastTime = nowTime;
        return;
      }

      if (trailing && !timer) {
        timer = setTimeout(() => {
          timer = null;
          lastTime = !leading ? 0 : new Date().getTime();
          const result = fn.apply(this, args);
          if (resultCallback) resultCallback(result);
          resolve(result);
        }, remainTime);
      }
    });
  };

  _throttle.cancel = function() {
    if (timer) clearTimeout(timer);
    timer = null;
    lastTime = 0;
  };

  return _throttle;
}
</script>
<style scoped>
.slide-verify {
  position: relative;
}

/* 图片加载样式 */
.slider-verify-loading {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  background: rgba(255, 255, 255, 0.9);
  z-index: 999;
  animation: loading 1.5s infinite;
}

@keyframes loading {
  0% {
    opacity: 0.7;
  }
  100% {
    opacity: 9;
  }
}

.slide-verify-block {
  position: absolute;
  left: 0;
  top: 0;
}

.slide-verify-refresh-icon {
  position: absolute;
  right: 0;
  top: 0;
  width: 34px;
  height: 34px;
  cursor: pointer;
  background: url("../assets/img/verImg/icon_light.png") 0 -437px;
  background-size: 34px 471px;
}

.slide-verify-slider {
  position: relative;
  text-align: center;
  width: 100%;
  height: 40px;
  line-height: 40px;
  margin-top: 15px;
  background: #f7f9fa;
  color: #45494c;
  border: 1px solid #e4e7eb;
}

.slide-verify-slider-mask {
  position: absolute;
  left: 0;
  top: 0;
  height: 40px;
  border: 0 solid #1991fa;
  background: #d1e9fe;
}

.slide-verify-slider-mask-item {
  position: absolute;
  top: 0;
  left: 0;
  width: 40px;
  height: 40px;
  background: #fff;
  box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
  cursor: pointer;
  transition: background 0.2s linear;
}

.slide-verify-slider-mask-item:hover {
  background: #1991fa;
}

.slide-verify-slider-mask-item:hover .slide-verify-slider-mask-item-icon {
  background-position: 0 -13px;
}

.slide-verify-slider-mask-item-icon {
  position: absolute;
  top: 15px;
  left: 13px;
  width: 14px;
  height: 12px;
  background: url("../assets/img/verImg/icon_light.png") 0 -26px;
  background-size: 34px 471px;
}
.container-active .slide-verify-slider-mask-item {
  height: 38px;
  top: -1px;
  border: 1px solid #1991fa;
}

.container-active .slide-verify-slider-mask {
  height: 38px;
  border-width: 1px;
}

.container-success .slide-verify-slider-mask-item {
  height: 38px;
  top: -1px;
  border: 1px solid #52ccba;
  background-color: #52ccba !important;
}

.container-success .slide-verify-slider-mask {
  height: 38px;
  border: 1px solid #52ccba;
  background-color: #d2f4ef;
}

.container-success .slide-verify-slider-mask-item-icon {
  background-position: 0 0 !important;
}

.container-fail .slide-verify-slider-mask-item {
  height: 38px;
  top: -1px;
  border: 1px solid #f57a7a;
  background-color: #f57a7a !important;
}

.container-fail .slide-verify-slider-mask {
  height: 38px;
  border: 1px solid #f57a7a;
  background-color: #fce1e1;
}

.container-fail .slide-verify-slider-mask-item-icon {
  top: 14px;
  background-position: 0 -82px !important;
}

.container-active .slide-verify-slider-text,
.container-success .slide-verify-slider-text,
.container-fail .slide-verify-slider-text {
  display: none;
}
</style>
